The present disclosure relates to a wireless communication and more specifically to a method and UE for cell reselection in connected mode thereof.
In general, wireless communication systems are widely deployed to provide various types of communication services such as voice, data, and so on. These wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations.
Operators with Time Division Duplex (TDD) based LTE deployment may have High Power User Equipment (HPUE) (Power Class 2) standardized for a TDD Band 41 in the 3rd Generation Partnership Project (3GPP). Further 3GPP has open study items for enabling the HPUE in other bands. The User Equipment (UE) can transmit up to 26 dBm in case of PC2 (instead of 23 dBm in PC3). The high transmit Power Class 2 (PC2) feature helps in coverage enhancement of the PC2 capable eNB by up to ˜30%. Hence, the HPUE is expected to remain in PC2 cells for a longer period of time compared to non HPUE devices. This is achieved by Pcompensation (one of the factor used in LTE cell selection as per 3GPP 36.304) difference between HPUE and non HPUE device.
However, there exists problem in current UE implementation which might negate the advantages of PC2 cells. These issues are explained as below:                a. 3GPP/3GPP2 standards define methods of Active mode handovers from eHRPD to LTE, but Mobile Network Operator (MNO) have not implemented due to additional overhead of new interfaces required for the same.        b. There are methods for Active eHRPD to LTE transition which periodically monitors LTE RAT when eHRPD is in connected state and force the UE(s) to switch to LTE without the need of additional network (NW) interfaces. However, following are the drawbacks of the same.        c. PC2 UE capabilities of device do not get automatically handled for handovers (like UMTS<->LTE or similar IRAT mobility).        d. There is no special handling of PC2 based devices in the aforesaid method for Active eHRPD to LTE transition.        e. So the devices supporting HPUE would NOT be able to take advantage of B41 PC2 during eHRPD<->LTE mobility scenarios.        f. User and operator experience could be devoid due to HPUE gains (may remain on eHRPD fr longer duration, poor TPUT etc.).        
It is well known that with PC2 network, the device(s) will have a 3 dBm of gain in their cell coverage.
For example, consider a scenario in which the UE is in mobility and is moving towards LTE PC2 cell coverage and eHRPD is in connected state. At first, the UE, in eHRPD connected state, can be configured to scan for LTE regularly (for example, LTE scan for every 60 sec) and shall acquire LTE service when LTE RSRP>a predefined threshold (i.e., −108 dBm) (as shown in FIG. 1A).
Referring to FIG. 1A, if at area(x) there is no LTE coverage then, the UE will obtain eHRPD services as per the standard communication protocol. Further, when the UE moves to area(y), then the UE starts scanning the neighboring LTE cells, but cannot acquire LTE services as LTE RSRP of the neighbor LTE cell is <−108 dBm. Furthermore, when the UE moves to area (z), the UE, finally, acquires the LTE services as the LTE RSRP of the neighbor LTE cell is >−108 dBm.
Active eHRPD to LTE transition Feature: Referring to FIG. 1A, if the UE is in a connected state on a less preferred system, then the UE can scan for more preferred LTE system without waiting for current data connection to go dormant/idle. Current Active eHRPD to LTE transition feature works as per below parameters (Table 1).
TABLE 1Active eHRPD to LTE transition Parameters Descriptionserving_thresholdECIO of serving eHRPD is below this value Target_threshold Reference Signal Received Power (RSRP) of LTE cell is above this value scan_interval LTE/Target cell scan periodicity
Consider another scenario, in which the UE is in eHRPD connected state and now moved to an area where LTE PC2 cell with weak signal is present, then the UE stays in this area (Stationary Scenario). At first, the UE, in eHRPD connected state, can be configured to scan for LTE regularly (for example, LTE scan for every 60 sec) and shall acquire LTE service when LTE RSRP>−108 dBm (as shown in FIG. 1B).
Referring to FIG. 1B, due to the weak LTE PC2 cell with weak signal at area(Y), the UE will never acquire LTE services even when LTE can be sustained at this RSRP as per HPUE.
Thus, it is desired to overcome a shortcoming described in the aforementioned scenarios.
The above information is presented as background information only to help the reader to understand the present disclosure.
The principal object of the embodiments herein is to provide a method and UE for cell reselection in a connected mode thereof.
Another object of the embodiments herein is to provide a method for determining power class (PC) capability of the neighboring cells based on a band of the one or more inter-RAT frequencies.
Another object of the embodiments herein is to provide a method for reselecting to a neighboring cell using the determined power class capability when the measured signal strength of the neighboring cell meets the pre-defined reselection threshold.
Another object of the embodiments herein is to provide an Active eHRPD to LTE transition feature enhancement for a HPUE device.
Another object of the embodiments is to identify neighbor LTE cells supporting PC2 in an eHRPD connected state.
Another object of the disclosure is to dynamically change the LTE threshold criteria for transitioning to LTE PC3 or PC2 neighbor cells.